Quenching of ZnO-char gasification

Abstract

In the gasification of char with zinc oxide improvement comprises the process of quenching the reactor effluent with recycled, cold CO product gas, thereby reducing the tendency for zinc vapor to react with any CO2 present to form blue powder.

We claim: 
     
       1. A process for the gasification of solid carbon containing materials which comprises: (a) heating in an entrainment bed reaction means under endothermic reaction conditions finely divided carbon containing particles with finely divided zinc oxide employing as heat source hot entraining sweep gas, thereby producing a hot gaseous stream comprising zinc, carbon monoxide, and traces of carbon dioxide,   (b) quenching said hot gaseous stream with cool recycle carbon monoxide, thereby condensing said zinc as molten zinc metal while avoiding substantially the formation of blue powder, and producing an off-gas stream of hot carbon monoxide,   (c) reoxidizing said molten zinc by contact with air in oxidation contactor means, thereby producing finely divided zinc oxide for recycle to said step (a), and nitrogen as a second off-gas stream,   (d) further heating a portion of said off-gas stream of hot carbon monoxide from said step (b) by indirect heat exchange with said oxidation contactor means step (c), thereby producing said hot entraining sweep gas for recycle to said step (a) to provide heat thereto,   (e) cooling by indirect heat exchange means a further portion of said hot off-gas carbon monoxide stream from said step (b) to provide said cool carbon monoxide quench gas, and   (f) withdrawing a further portion of carbon monoxide gas as product.   
     
     
       2. The process according to claim 1 wherein said carbon is provided by coal, coke, char, tar sand, peat, oil shale, lignite, or rubber scrap. 
     
     
       3. The process according to claim 2 wherein the finely divided particles of carbon feed are no more than about 0.4 mm in diameter on the average. 
     
     
       4. The process according to claim 3 wherein said contacting of said carbon feed particles with said zinc oxide particles is conducted at a temperature in the range of about 1800° F. to 2200° F., a pressure of about 0.5 to 1.5 atmospheres. 
     
     
       5. The process according to claim 4 wherein said quenching recycle carbon monoxide is at a temperature in the range of about 0° F. to 140° F., employing a pressure in the range of about 1 to 1500 psi. 
     
     
       6. The process according to claim 5 wherein said entraining sweep gas passes downflow through said reaction means.